Protecting life is supreme

Lord Buddha Shakyamuni:

Life is the root of all qualities. Hence, protecting life is a gift that grants all forms of happiness. Among all forms of generosity, the mental state of wishing to give life is supreme. Among all forms of discipline, the discipline of giving life is the supreme way to gain rebirth in the higher realms.

If the practice of such discipline is dedicated toward the enjoyment of objects that serve as causes of affliction and craving, then one will become Brahmā, Māra, or Śakra.

If it is dedicated to becoming a great human being, then one will become a universal monarch, possessing the seven treasures and ruling the four continents. If it is dedicated to becoming a great asura, one will rule the realm of the asuras. If it is dedicated to becoming a great yakṣa one will rule the realm of the yakṣas.

This great compassion is the seed of the sacred Dharma. It is a protection against cyclic existence and a lamp for those who are lost in the darkness of cyclic existence. Such is the practice of refraining from killing. By giving up killing one cultivates love and becomes a compassionate being.

Deciding to refrain from killing brings purity and joy. When one is unable to actually save others, one should remain impartial. This will make one’s mind rest in the four abodes of Brahmā.

In essence, the roots of virtue that ensue from having given up killing are inconceivable because they accomplish whatever aim one may dedicate them to in whatever applicable way.

As an analogy, when an expert goldsmith works with fine gold, he can turn it into anything he wants: ornaments, vases, human figures, or Buddha figures. Similarly, someone who guards against killing and maintains that practice unerringly without violating it may accomplish whatever aim he or she is dedicated to in whatever applicable way.

Thus, those who give up killing are close to the transcendence of suffering. They will enjoy the company of spiritual teachers and possess the fortune of benefiting themselves and others. They are a field of merit for hell beings, animals, and starving spirits.

Within cyclic existence they possess and follow the Dharma. They will accomplish the ideals of those who possess the Dharma and also become stable in this accomplishment.

They are not frightened or oppressed by rulers, robbers, water, or fire. Rather, they find joy within. They are seen as unassailable by other peers who possess the Dharma. Thus, killing should be given up. 

(From the Sutra of The Noble Application of Mindfulness of the Sacred Dharma)